1. Field of the Invention
The present invention is generally related to a pencil sharpener, and more particularly to an automatic pencil sharpener.
2. Description of the Related Art
A typical electric pencil sharpener comprises an electric motor, a gear train, a cutter assembly, and a receptacle for receiving a pencil or a pencil alignment device. The sharpener further comprises a switch for activating the motor, e.g. upon insertion of a pencil. When the pencil is positioned in the receptacle, the motor transfers its power to the cutter assembly through the gear train. The pencil is sharpened by a blade of the cutter assembly. Numerous innovations for pencil sharpeners have been provided in the prior art that will be described. Even though these innovations may be suitable for the specific individual purposes to which they are addressed, however, they differ from the present invention.
Pencil sharpeners exemplifying one or more of these characteristics are shown in U.S. Pat. No. 2,335,148 to Hoffman, U.S. Pat. No. 2,545,779 to Harrison, U.S. Pat. No. 2,822,781 to Burton, U.S. Pat. No. 2,900,958 to Johnson, U.S. Pat. No. 3,134,365 to Hori, and U.S. Pat. No. 4,601,316 to Verdi.
An early typical pencil sharpener, disclosed in U.S. Pat. No. 5,394,613 to Ku teaches a spring-driven pencil sharpener comprising a top cap having a top opening to receive a pencil and two corresponding slots to receive a fastening device that include a couple of hollow frames. The pencil sharpener comprises a housing which is constructed with a pair of coupling castings, each of which is accompanied by a lateral cover for disposing a pencil blade set and a spring-driven automatic device. The outline of the housing is preferably designed to cooperate with that of the cap to form an egg-like shape that is comfortable to the hand and looks nice. However, the pencil to be sharpened in the typical sharpener is manually fed into the housing, which is inconvenient comparing to an automatic one. In addition, the holding force for the pencil is provided by the user and is unstable, so the pencil sharpener is easily jammed.
Another conventional pencil sharpener, disclosed in U.S. Pat. No. 6,065,514, comprises a sharpening sub-assembly for sharpening pencils and first and second external shells having internal ribs defining surfaces for supporting the sharpening sub-assembly. The sharpening sub-assembly comprises an electric motor, a gear assembly, and a cutter assembly including a cutter gear module having an annular ring gear acting as a carrier support. The sub-assembly houses a pencil insertion switch and a receptacle presence switch. However, the holding force for the pencil is still provided by the user and is still unstable. The pencil sharpener is easily jammed.
It is apparent that numerous innovations for pencil sharpeners have been provided in the prior art. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they are addressed, the pencil is still manually fed with a holding force that is difficult to control such that jamming frequently occurs.